1. First, historical trend data can be stored in the local hard disk of the server, which is usually the hard disk space reserved when installing the system. The specific location can be determined by looking up the path of historical trend data on the server or viewing the storage settings in the system settings.

2. Secondly, historical trend data can be stored in external storage devices connected to the server, such as tape libraries and hard disk arrays. In this case, the specific location can be determined by looking at the external storage devices connected to the server.

3. Recent historical trend data can be stored in databases, such as Oracle and SQLServer. In this case, you can determine the specific location by looking at the database configuration on the server.